1. Field of the Invention
The present invention relates generally to control systems for glassware forming machines and in particular to electronically controlled individual section glassware forming machines.
2. Description of the Prior Art
The individual section or IS glassware forming machine is well known and includes a plurality of sections each having means for forming glassware articles in a timed, predetermined sequence of steps. Typically, the sections are fed from a single source of molten glass which forms gobs of molten glass for distribution to the individual sections in an ordered sequence. The sections are operated in synchronism at a relative phase difference such that one section is receiving a gob, while another section is delivering a finished glassware article to a conveyor, and one or more other sections are performing various ones of the intermediate forming steps.
The forming means in each section are typically operated from pneumatic motors or actuators. In early prior art machines, the pneumatic motors were controlled by a valve block which in turn was controlled by a timing drum for each section driven from a line shaft which synchronized all parts of the machine. One of the limitations of the timing drum was the difficulty of manually adjusting the timing during the operation of the machine.
One solution to this problem was to replace all the timing drums with an electronic control means. Various types of electronic control systems for glassware forming machines have been developed. Once such control system is disclosed in U.S. Pat. No. 4,152,134 issued to Dowling et al. An electronic control means of the type disclosed in the above-mentioned patent permits timing changes to be effected electronically so that the adjustments are easier to perform and the accuracy of the adjustments is greatly increased over the prior art controls.